Thursday, March 13, 2014

US Navy F-4 EW development - Revisited

Ok, let’s try this again.  After much research and a heap of help from Mike France and Craig Kaston, I think I can present a better picture of the sequence of EW fits to the Navy Aircraft.   I will be presenting these in several parts, so keep coming back to see what has been posted. If you are new to this subject or these posts, I suggest you start by reading the first section so you get some background. 

Just click on the links to read more about each system.


  • Historical Background
  • S-76 Dvina (NATO: SA-2 Guideline) SAM

1965 / 1966

Equipment installed without Airframe Change (AFC):
AFC-331 Pt. 1 (ECP-F-4-703 &703S1) installs:
F-4B, F-4J*
The KY-28 was installed on all aircraft, ships, and fixed bases in the Vietnam theater of operations starting in 1965. It synced with the KY-38 man pack used by ground forces and KY-8 vehicular unit. These units provided secure encrypted voice communications.
* F-4Js would come off the assembly line with this equipment installed.

1966 / 1967

Equipment installed without Airframe Change (AFC):
Installed on all F-4B aircraft for VF-92 and VF-96 on CVAN-65 USS Enterprise during its 1966-1967 Vietnam cruise. These were the only aircraft with this equipment.
Installed on 4-5 aircraft for VF-151 and VF-161 on CVA-64 USS Constellation, 4-5 aircraft for VF-14 and VF-32 on CVA-42 USS Franklin D Roosevelt, and 4-5 aircraft for VF-96 on CVAN-65 USS Enterprise during their 1966-1967 Vietnam cruises. This equipment was removed after their cruise.
AFC-296 (ECP-F-4-707R1) installs:
Sent as kits and installed on-board during the 1966-1967 Vietnam Cruises of CVA-64 USS Constellation, CVA-42 USS Franklin D Roosevelt, and CVAN-65 USS Enterprise. Future deployments had the APR-27 installed prior to departure.

1967 / 1968

This is a time when the changes made to the EW equipment gets sort of messy. There were a lot of new EW developments that were happening in quick succession. With these changes happening so quickly it isn't always easy to tell how an aircraft was configured by merely looking at fairings. This is because we often see that a change was made and the old fairings weren’t removed, just left empty (or full but disconnected) or that old fairings were used with new equipment installed. 
Equipment installed without Airframe Change (AFC):

(This will be referred to as "AN/APR-25 Mod 1" for our purposes - click here for more information.)

This was a pre-Shoehorn fit as seen only in aircraft of VF-142 and VF-143 on CVA-64 USS Constellation during its 1967 Vietnam cruise.
Project Shoehorn was a program providing a complete suite of EW equipment to the F-4Bs. It was considered "state of the art" at the time, and several doors had to be added/enlarged to provide room to "shoehorn" in all the needed equipment.

AFC-333 (ECP-F-4-707R1S1, S2) installs:
  • Melpar Inc. AN/APR-30 S/C/X-band Radar Homing & Warning System
AFC-334 (ECP-F-4-761S1) installs:
  • Magnavox AN/ALQ-91 IFF Countermeasures System
First seen on CVA-59 USS Forrestal with VF-11 and VF-74 on its tragic 1967 Vietnam cruise. It should be noted that the Forrestal's squadrons showed a mix and match of aircraft on this cruise. Some were fully configured with the new shoehorn fit while others were not. It has been suggested that delays in the equipment becoming fully operational meant that the Forrestal had to sail before all her F-4Bs were fully modified to the "Shoehorn Mod 1" spec. I would imagine that the unmodified aircraft would be paired with a Shoehorn aircraft to offer some type of protection.

The disastrous fire on ship soon after the start of combat operations ended any mid cruise updates and so her surviving F-4B aircraft were not finally brought up to the full spec until her return to the USA in September 1967 with all being updated by early 1968. These surviving aircraft would appear to be the same as those modified under AFC-339 and AFC-375 in 1967 having the original APR-30 fairings but being equipped with APR-25 under the skin.

CVA-43 USS Coral Sea with VF-151 and VF-161 during her 1967-1968 Vietnam cruise ws the only carrier to bring a full compliment of  "Shoehorn Mod 1" equipped F-Bs into the Vietnam conflict. The USS Coral Sea along with the USS Forrestal were the only carriers to deploy the "Shoehorn Mod 1" equipped F-4Bs into Vietnam.

AFC-339 (ECP-F-4-761) and AFC-375 Pt.1 (ECP-F-4-830) installs:
  • Magnavox AN/ALQ-91 IFF Countermeasures System
AFC-375 Pt.1 (ECP-F-4-830) and AFC-375 Pt.2 (ECP-F-4-707R2) installs:
  • Applied Technology Inc. AN/APR-25 S/C/X-band Radar Homing & Warning System
It would seem that the Navy was not happy with APR-30 and decided to replace it with the proven APR-25 RHAW system and did so with many aircraft already on the mod line being prepped for APR-30 Shoehorn Mod 1.

Appears on F-4Bs of VF-21 and VF-154 on the CVA-61 USS Ranger, VF-11 and VF-213 on the CVA-63 USS Kitty Hawk, and VF-92 and VF-96 on CVAN-65 USS Enterprise on their 1967-1968 Vietnam cruises.

1968 / 1969

AFC-339 (ECP-F-4-761) and AFC-375 Pt.1 (ECP-F-4-830) continues to install:
  • Magnavox AN/ALQ-91 IFF Countermeasures System
AFC-375 Pt.1 (ECP-F-4-830) and AFC-375 Pt.2 (ECP-F-4-707R2) continues to install:
  • Applied Technology Inc. AN/APR-25 S/C/X-band Radar Homing & Warning System

The first aircraft to be modified to "Shoehorn Mod 3" specs in 1968 were those on the USS Constellation with VF-142 and VF-143. They differed from what became the standard 1968 fit in that while they did indeed have a single fairing fin cap already in place from their 1967 cruise they also were fitted with the original APR-30 hook shaped chin pod fairing. It is thought this was nothing more than using up the last of the available stocks of these fittings and indeed a small number of the first Marine aircraft to go into the Shoehorn project acquired the same fit.

New aircraft coming into VF-151 and VF-161 on the Coral Sea were the first to get the new and correct shaped antenna fairings associated with AFC-339 and AFC-375. It should be noted that the aircraft assigned in 1967 that were to stay with the Coral Sea's squadrons retained their original APR-30 fairings but had the revised fairings fitted when they returned Stateside at the end of the 1967 / 1968 Vietnam cruise. 

1968 saw the introduction of the F-4J to Vietnam combat operations deploying with VF-33 and VF-102 on CVA-66 USS America. The aircraft assigned to these squadrons were the first Navy F-4Js to get the shoehorn mods on the production line and the first of them was BuNo. 155529.

AFC-352 (ECP-F-4-687S3) installs:
  • Hazeltine AN/APX-76 Air-to-Air IFF System
AFC-388 (ECP-F-4- 840S1, S2) installs:
  • Applied Technology Inc. AN/APR-25 S/C/X-band Radar Homing & Warning System
  • Magnavox AN/ALQ-91 IFF Countermeasures System
  • Hazeltine AN/APX-76 Air-to-Air IFF System

The USS America was followed in to combat operations by (Shoehorn Mod 3) modified F-4B aircraft of VF-151 and VF-161 on CVA-43 USS Coral Sea,
VF-21 and VF-154 on CVA-61 USS Ranger with (Shoehorn Mod 4) F-4J aircraft,
VF-11 and VF-213 on CVA-63 USS Kitty Hawk with
(Shoehorn Mod 3)  F-4Bs and VF-92 and VF-96 on CVAN-65 USS Enterprise with (Shoehorn Mod 3) F-4Bs.

F-4B aircraft from this 1968 / 1969 deployment period world wide would show a mix of aircraft with the original AN/APR-30 fittings of Shoehorn 1&2 and the later AN/APR-25 fittings of Shoehorn 3. But it is worth noting all aircraft would have the same AN/APR-25 RHAW system under their different skins.

It should be noted that USMC aircraft in the Pacific area finally got their own aircraft straight from the new mod lines set up in Japan and in the Philippines during this 1968 /1969 time frame. Previously any shoehorn aircraft seen with the Marines would have been ex US Navy aircraft swapped out when the Navy deployments were done. There would always be a lot of aircraft switching between Navy and Marine squadrons in this period.

During this period Atlantic fleet carriers would also start to get AN/APR-25 Shoehorn equipped F-4s (CVA-59 USS Forrestal being the only Atlantic carrier to have AN/APR-25 equipped aircraft prior to this time).


APC-524 (ECP-F-4-1023R2S1, S2) installs:
  • Applied Technology Div. (ITEK) AN/ALR-45 Countermeasures Receiving Set
F-4B, F-4J
  • Raytheon AN/ALR-50 Radar Receiving Set
F-4B, F-4J


AFC-541 (ECP-F-4-1035S1) installs:
F-4J*, F-4N**
*The first F-4Js did not have this system installed during assembly, but looking at my resources I begin to see a few with the modification appearing by late 1972. But there are also many pictures without the modification in this time frame so the conversion is by no means complete.  Pictures from 1975-76 show that most aircraft had been converted by this time.

** The first F-4Ns did not have this system installed initially during conversion, but were retrofitted by 1975. The first carrier deployment of F-4Ns was on CVA- USS Midway out of Yokosuka, Japan from September to October 1973. These aircraft did not have the shoulder wave guide antennas of AN/ALQ-126 fit yet.

Revision History:
  • 29 MAR 2014 - Added pages for Shoehorn Mod 4
  • 24 MAR 2014 - Added pages for AN/APR-25, AN/ALQ-51/100 & AN/ALQ-126
  • 19 MAR 2014 - Added pages for Shoehorn Mod 1, 2, & 3
  • 13 MAR 2014 - Original Post
  • Michael France and his unending patience and tremendous work on F-4 Phantom II changes
  • Craig Kaston and his patience and help with the "Navy Way" of doing things

My Experience with the F-4 Phantom

My experience with the F-4 Phantom II began in 1976 as a newbie airman - a fresh honor graduate of the USAF aircraft maintenance program at Sheppard AFB, Wichita Falls, Texas.  My first assignment was to the 81st Tactical Fighter Wing  based at RAF Bentwaters / Woodbridge near Ipswich, England.  Bentwaters / Woodbridge was a twin base which were located just a few miles from each other, with Bentwaters being the main base with all the administration functions as well as the 91st and 92nd Tactical Fighter Squadrons, and Woodbridge having the 78th tactical fighter squadron and the 67th Air Rescue and Recovery Squadron operating the HC-130H Hercules and HH-53 helicopters.

 When I arrived in the UK I was assigned to RAF Woodbridge and the 78th "Bushmasters."  RAF Woodbridge was a very small and quiet base carved out from the Rendlesham Forest which surrounded it.  In 1943 when the base was constructed to be an emergency air strip for returning damaged B-17s, over a million trees were cut down to make room for the base.

When I arrived at the flight line for the first time and walked up to the F-4D I remember how awed I was with this huge, powerful, ugly beast. I was placed into the capable hands of SSgt. Dennis Thompson to serve as his lackey until he figured I wouldn't do anything dumb that would result in the destruction of the aircraft, himself, or myself - pretty much in that order (an newbie airman was easily replaceable).   Dennis had previous experience with the F-100, F-105, and F-106 before he came to work on the F-4 and was ready to tell me all about the advantages and disadvantages of working on the F-4 over the other aircraft.  Overall I received the impression that he liked working on the F-4 and he taught me a lot in our time together. During the first few months I was able to avoid the usual newbie hazing (Hey airman, go get me a bucket of prop wash, sky hooks, or 50 feet of flightline, etc.).  I had had grown up around airplanes and was able to quickly see through all of the nonsense.

The 81st Tactical Fighter Wing had a responsibility to USAFE and NATO to provide a strike deterrent to keep the Reds from pouring through the Fulda Gap with thousands of tanks and troops. This was to be done by dropping tactical nuclear bombs on their heads.  In fact, both bases had fenced in alert areas which had aircraft loaded with B61 nuclear bombs, ready 24x7 to go into harms way. 
We had several exercises each year to prepare us for the day when the Russians would invade.  This started with a maintenance push to get the maximum number of aircraft ready and configured for the mission.  Then the planes were roped off, Security Police were stationed as pickets, and we then had to use the two man concept (a huge pain in the er, bum) where everything you did required two people to make sure no one person could sabotage the weapon system (as it was referred to once it was mission ready).  Weapons personnel would come and load BDU-36 shapes (a kind of practice B61 filled with concrete to the right weight & balance) and any other defensive weapons that were tasked.  Now the weapon system was considered "cocked" (like you would a revolver). And we would sit and wait.  Once the weapon system was cocked we couldn't get near the aircraft unless one of three things happened.  1. The aircraft began pissing JP4 or other vital fluids all over the ramp, 2. The klaxon would go off and we had to launch the birds for a mission as configured (to the range to drop their loads of metal and cement), or 3. The all clear was given and we would begin to tear everything down, defuel and drop the extra external tanks, and get them ready for the day-to-day operations again.

Our secondary mission for NATO was precision delivery of weapons, for which we used the AN/AVQ-23 Pave Spike pods with Paveway LGBs, and the AGM-65 Maverick missile.  Normally our weapons load out really wasn't anywhere near what the F-4 was capable of.  Rarely were AIM-7 Sparrows loaded except on the alert birds. For normal day-to-day range work a single AIM-9 Sidewinder practice round was loaded (operational seeker head on an inert rocket motor) and one or two SUU-21 practice bomb dispensers.  On occasion there was a SUU-23 gun loaded on the centerline station or an AGM-65 Maverick practice round loaded on the inboard pylon.  Once when I was TDY (temporary duty) at Zaragoza AFB, Spain, I was able to fly out to the range on my day off and watch the squadron drop bombs and strafe targets from the observation tower.  It was quite amazing to watch these birds swoop in at rather high speeds and still hit their target with bombs and bullets. 

The Yom Kippur War in the middle east inspired our fearless leaders to wonder if the USAF could support the effort that was needed for the Israeli Air Force to repel borders and help turn the tide of the Syrian/Egyptian invasion.  This resulted in a series of "max-effort" exercises where we would fly around the clock for a week, turning aircraft around as quickly as possible and keeping them flying through extreme maintenance efforts.  We all hated these, and by the end of the week we were tired, grumpy, and sick of it all.  Practice without the adrenalin that comes from actually being invaded kind of leaves you flat and the effort is exhausting.  I hate to think what these exercises cost in fuel and spare parts, as well as wear and tear on the already ten-year old aircraft.  And of course I don't think it did much to our public relations in the nearby hamlets and villages as our aircraft roared  into the sky at all hours of the day and night (and believe me, the F-4D makes a ton of noise taking off in full burner).  One thing these exercises did do was forge teamwork among the maintenance people.  After one night flight my plane (F-4D 66-7716) came back about 1:00AM with a hydraulic leak in the right center leading edge flap.  This was in December and it was foggy and as cold as could be. After securing the plane and doing my post-flight inspections, I enlisted some help from some of the other crew chiefs to tear apart the flap, so that it was ready for the hydraulic troops when they arrived.  The next thing I knew our flight chief, Master Sargent Paul Day, was pulling up with his pickup truck.  He gets out in his immaculately clean and starched fatigues, and starts relieving us one at a time so that we could sit in his warm truck and have a hot cup of coffee.  There he was turning a speed wrench like a lowly airman again.  He stayed until the whole project was done and we were ready for the next days flight. I am sure those fatigues were never the same after being soaked in hydraulic fluid, but that day I had a lesson in what true leadership really looked like.

Because the F-4D was my first aircraft, I assumed that all planes took this much maintenance to keep them flying.  Each day after flight I would do a post flight inspection and have the necessary specialists show up to fix whatever needed fixing.  It is true testament of the F-4 that it was such a effective weapons system for as long as it was.  At that time I called the F-4 a "vacuum tube jet flying in a transistor world".  And it kept on serving effectively into the era of integrated chips and digital electronics.  It was never the prettiest girl at the dance, and it wasn't the best at every task that was given it, but it was definitely the first true multirole fighter, and it could hold its own doing just about anything asked of it.

Thursday, November 28, 2013

What? A Phantom for the US Army?

Ever since the Key West Agreement of 1948 (pet name for the policy paper titled “Function of the Armed Forces and the Joint Chiefs of Staff”), which limited Army aviation activities to reconnaissance and medical evacuation purposes and put severe weight restrictions on any aircraft, the Army has maintained that the Air Force was too strategic (ie nuclear) minded and not giving enough attention to the tactical and logistical needs of the Army.  As a result the Army often pushed the envelope of the agreement limits, citing the need for better transport and close air support assets.

To try and smooth the troubled waters, in 1952 a memorandum of understanding was reached between USAF Secretary Thomas Finletter and US Army Secretary Frank Pace that removed all weight restrictions on helicopters operated by the Army.  It did however; place an arbitrary 5,000 pound weight restriction on any fixed-wing aircraft.

During the late 1950s the Army Aviation Test Board and the Aviation Combat Developments Agency (ACDA) began to jointly explore the feasibility of using Army-operated fixed-wing jet aircraft in the artillery adjustment, tactical reconnaissance, and ground attack roles.  In early 1958 three Cessna T-37As were borrowed from the Air Force for a one year evaluation program dubbed Project LONG ARM.  The Army’s evaluation found the T-37 to be ideal for their needs, and the Aviation Board and the ACDA recommended quantity procurement of the type.  But the Air Force, citing the Key West Agreement, put pressure on the Army and eventually the program was dropped. 

But the Army wasn’t done, the battle may have been won by the Air Force, but the war had just begun.  In 1961 the Army Aviation Test Board and the ACDA once again stirred the pot by trying not one, not two, but three jet aircraft types in a competitive “fly-off”.  The aircraft chosen were the Northrop N-156 lightweight fighter prototype, The Douglas A-4 Skyhawk, and the Fiat G.91.  Ostensibly these aircraft were to be used as tactical reconnaissance and target spotting and artillery adjustment roles, but it was hard not to notice that each of these aircraft had offensive weapons capability, which was clearly contrary to the Key West Agreement.  Again the Army’s tests were in vain because Air Force pressure again forced the Army to scuttle its plans for jet fixed-wing aircraft.

Meanwhile the Army had acquired a fleet of fixed-wing aircraft ranging from the Piper L-4 (730 pounds empty) to the DeHavilland-Canada U-1 Otter ( 4,431 pounds empty).  All of these aircraft easily fit under the limitations of the Pace-Finletter MOU of 1952.  Air Force apprehension rose when the Army in 1962 awarded a contract to DeHavilland- Canada  for the CV-2 Caribou (later the C-7).  This aircraft was exactly what the Army wanted, a rugged and reliable aircraft that could haul nearly 4 tons of cargo or 40 passengers into and out of the roughest forward air fields.  The Army quickly made it the poster child of Army Aviation.  Oh, did I forget to mention that it weighed 16,920 pounds empty?  Even though it was a tactical cargo aircraft, which was supposedly taboo, the Army  justified it by a new concept the Army was incorporating called “Air Mobility”.

By now you are wondering “what has all this got to do with the Phantom II?”  Be patient, I’m almost there.

Naturally the Air Force was a bit peeved.  The Army had not only purchased a tactical cargo aircraft, it had armed helicopters (which the Army was not supposed to do), and to add salt to the wound, the US Army talked the US Marine Corps into sponsoring a battlefield observation aircraft from Grumman, both sides knowing full well that the Navy would never buy it for the Marines.  But as a result the Army “found” this nice “little” Marine aircraft that nobody wanted and decided to be nice and order a bunch.  Enter the Grumman OV-1 Mohawk.  A bit heavy at around 11,500 pounds empty, but it was the perfect battlefield observation aircraft and it was really needed in a hot spot that was heating up called Vietnam.  It even had pylons which could carry fuel tanks (not to mention the odd gun pod or missile launcher). The Air Force was not amused.

Finally we get the Johnson-McConnell Agreement of 1966, where the Army agreed to turn over its fleet of Caribous and the newer Buffalo, and pursue their development of VTOL aircraft on a joint basis with the Air Force.  The Air Force agreed to let the Army continue to develop and operate rotary wing aircraft, without weight restrictions, and would not interfere with their tactical helicopter operations (even armed helicopters) in support of the Army’s mission.  The one aircraft that was an exception was the Mohawk which the Army was permitted to continue to use (It really was a great battlefield observation aircraft with its side looking radar and other sensors).

Sorry for the history lesson, but it is necessary to understand the climate that the McDonnell proposed Phantom II ground support aircraft for the Army was introduced into.

In 1961 McDonnell drew up specifications for two attack aircraft based on the F-4H airframe.  I don’t know if they ever were presented to the Army, but I assume they were because they are on the books as Models 98DA and 98DB with the US Army as the proposed customer.  This would have been about the time of the evaluation fly-off of the N-156, A-4, and the G.91, so I imagine that McDonnell didn't want to get left out if the Army was going for jet aircraft.


The Model 98DA was a model F4H-1 modified for the Army ground support mission. It was offered in two versions - G-1 and alternate G-1 with changes as follows:
  1. Two place aircraft.
  2. Remove all electronic equipment items and replace with close support equipment to provide visual delivery of ground support weapons and visual lay down capabilities.
  3. Replace single main landing gear tire with dual 30 x 7.7 tires.
  4. Deactivate wing fold and remove catapult and arresting gear.
  5. Remove Sparrow III missiles and supporting equipment and electronics.
  6. Remove equipment refrigeration package for equipment cooling, utilizing cabin refrigeration unit to also cool equipment.
  7. Add cartridge starters and battery.
  8. Replace present arresting gear with lightweight hook.
  9. Add IFR boom receptacle.
  10. Powered by two General Electric J79-GE-8 turbojet or Allison AR-168-18 (Allison built Rolls Royce Spey RB-168) turbofan engines.
  11. (Alternate G-1 only) Add one M-61 Vulcan aircraft cannon with 930 rounds 20mm ammunition.

The Model 98DB was the same as model 98DA but further modified for the Army ground support mission with changes as follows:
  1. Single-seat Aircraft
  2. Remove rear seat and all associated controls, instruments, and equipment. (Space available for equipment growth and/or reconnaissance capability)
  3. Remove rear canopy glass and replace with sheet metal.
  4. Remove rear canopy electrical and jettison equipment and modify manual controls to open and close hatch.
  5. Eliminate Central Air Data Computer (CADC) and flight control group equipment.
  6. Remove IFR Probe and all associated equipment.
  7. Remove variable bellmouth from engine duct, keep bellmouth controller to control variable inlet ramps.
  8. Powered by two General Electric J79-GE-8 turbojet engines.

It is evident that these proposed aircraft were clearly a much stripped-down attack version of the Phantom II.  Almost all of the air-to-air capability has been stripped away.  Some of the proposed changes indicate that this wasn’t intended to be a high-speed aircraft.  The dual main gear, obviously intended to help the aircraft operate out of rough, forward area airstrips, would have hung out into the airstream, and even if fairings would have been utilized to blend it into the wing, they would have had a performance hit.  The elimination of the CADC and bellmouth would also have curtailed any high-speed / altitude flight.  This aircraft was intended to be a mud-fighter – a low altitude, subsonic aircraft that could manually deliver an impressive load of munitions on a given target.

I am sure that the Army didn't show a lot of interest because, even in the stripped down state presented by these proposals, the F-4 was just too much of an aircraft both weight-wise and complexity to operate out of primitive forward area airstrips.  Maintenance would have been a head ache, and even with the dual main wheels, I am sure it would sink into any soft soil it would come in contact with.  The T-37, which was the early favorite, would have probably served the Army well in their intended role.  But in the end the Army didn't pursue any jet aircraft, and the Air Force won the war in the end.

  1. US Army Aircraft Since 1947, by Stephen Harding
  2. Note by the Secretaries to the Joint Chiefs of Staf- Functions of the Armed Forces and the Joint Chiefs of Staff – Reference J.C.S 1478 Series, dated 21 April 1948
  3. A History of Army Aviation: From Its Beginnings to the War on Terror, by James Williams
  4. Tactical Airlift. United States Air Force in Southeast Asia, by Ray Bowers
  5. McDonnell List of Proposed Models, dated 1 July 1974


28 November 2013 – Initial Post